glucose catabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways resulting in the breakdown of glucose, the aldohexose gluco-hexose. [GOC:ai]

Glucose catabolism, also known as glycolysis, is a fundamental metabolic pathway that breaks down glucose, a simple sugar, into pyruvate. This process occurs in the cytoplasm of cells and is crucial for generating energy in the form of ATP (adenosine triphosphate). Here's a step-by-step breakdown:

1. **Phosphorylation:** Glucose enters the cell and is phosphorylated by ATP to form glucose-6-phosphate. This initial step consumes energy but prepares glucose for further reactions.
2. **Isomerization:** Glucose-6-phosphate is converted to fructose-6-phosphate.
3. **Second Phosphorylation:** Fructose-6-phosphate is phosphorylated again by ATP to form fructose-1,6-bisphosphate. This further commits the molecule to the pathway.
4. **Cleavage:** Fructose-1,6-bisphosphate is split into two three-carbon molecules: glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP).
5. **Interconversion:** DHAP is converted to G3P, ensuring both molecules proceed through the next steps.
6. **Oxidation and Phosphorylation:** G3P is oxidized and phosphorylated, producing NADH (nicotinamide adenine dinucleotide) and 1,3-bisphosphoglycerate.
7. **Substrate-level Phosphorylation:** 1,3-bisphosphoglycerate transfers a phosphate group to ADP, generating ATP and 3-phosphoglycerate.
8. **Isomerization:** 3-phosphoglycerate is converted to 2-phosphoglycerate.
9. **Dehydration:** 2-phosphoglycerate loses water to form phosphoenolpyruvate.
10. **Final Substrate-level Phosphorylation:** Phosphoenolpyruvate transfers a phosphate group to ADP, generating ATP and pyruvate.

The net products of glycolysis per glucose molecule are:

* 2 ATP molecules
* 2 NADH molecules
* 2 pyruvate molecules

Pyruvate can then be further metabolized under aerobic conditions in the mitochondria via the citric acid cycle and oxidative phosphorylation, yielding significantly more ATP. Alternatively, under anaerobic conditions, pyruvate can be converted to lactate, allowing glycolysis to continue without oxygen. This process is crucial for many organisms, including humans, as it provides a continuous supply of energy for various cellular functions.'
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Proteins (3)

Compounds (17)